Jets defenders Tarek Elrich and Adam D'Apuzzo are under injury clouds while 17-year-old defensive midfielder Ben Kantarovski is also in doubt after a bout of the flu as well as suffering the pressure of High School exams.

With key defender Ljubo Milicevic still sidelined with a foot injury Culina is understandably worried with his defensive stocks ahead of Friday night's match at Suncorp Stadium.

"We have a few injuries we weren't expecting - Adam D'Apuzzo has a calf injury and Ben Kantarovski has been ill and has had the HSC so in fact he hasn't trained at all, which is not ideal," Culina said on Wednesday.

"We have got some options but our big problem is defence, particularly if Tarek or D'Apuzzo were unavailable - we don't have too many options on the sides of the defence, or in the middle of the defence."

"But that is what we have got so we can't do too much more about it."

Kantarovski looks the player to most likely to miss Friday night's match.

Although his health is improving he has not figured in training so far this week. Compounding the problem is the fact the 17-year-old will travel to Queensland with team on Thursday and then sit a Higher School Certificate exam on Friday afternoon, just hours before the match.

"He has an exam on Friday which is a bit of a concern," said Culina.

"The club has organised for him to sit his exam in Brisbane at about one o'clock in the afternoon, so it is not ideal."

"But whether Ben plays on Friday night or not he leaves for two weeks so he will miss the games against Wellington and the Fury, so we are very short of defensive cover."

Elrich, who signed for the club for another two years this week, went into last week's crucial derby clash against the Central Coast Mariners only 60 percent fit with a groin injury.

It didn't show, however, as the 22-year-old played a solid game in defence and set up his side's first goal to help the Jets to a 2-1 win, and he is confident he will play in Friday's clash against Brisbane.

"I think it was just after the Melbourne game it was a bit sore but I got a lot of treatment and Branko gave me the day off just to get it right." Elrich said.

"It is just a recurring injury where my muscle is coming from the bone in my groin, but I have been told by (team phsyio) Neil Halpin, that I won't do much more damage to it if I play. At the end of the day if I make a mistake it won't be because of my groin."

Midfielder Jobe Wheelhouse, who has recently returned from a knee injury is an option for the Jets in the defence, while skipper Matt Thompson could revert back to the backline after being pushed into the midfield in last week's match.

While Culina is somewhat concerned with the defensive stocks, he is more than happy with the stabilising effect of veteran defender Angelo Costanzo, who starred in the centre of a three-man defensive line for the Jets in last week's 2-1 win over the Mariners.

After a few weeks out of the squad, Costanzo was recalled to starting side to take over in the central holding role from Kantarovski, who was pushed forward into a five-man midfield after leaking three goals as central defender the week before against Melbourne.

"Angelo Costanzo gives us that communication," Culina said. "It takes players a bit longer to learn that part of the game - that discipline, and he has that part to his game and I think we saw the outcome last week."

"Everyone was more relaxed and Angelo certainly made it a lot easier for (goalkeeper) Ben Kennedy and Nikolai (Topor-Stanley), who by nature are quiet individuals - he was organising and all they had to do was concentrate on playing good football."